Guyatone PS-008 Parametric Equalizer

Turning this control clockwise (in the + direction) emphasizes (+ 18dB = 8 times) the band set by the Frequency control, and turning it counterclockwise (in the - direction) attenuates (-18dB = 1/8) the same. At the center (0 position) of the knob, meanwhile, the frequency characteristics become flat irrespective of the other two knobs' position

Width

This knob controls the width of the frequency band set by the Frequency control. Turning it clockwise decreases (1 octave) the width, and turning it counterclockwise increases (2 octaves) the width.

Frequency

This knob controls the frequency to be emphasized or attenuated. Turning it clockwise shifts the center frequency toward high tones (5,000Hz), and turning it counterclockwise shifts the same toward low tones (70Hz).